A concatenated transmission system according to the embodiment generates OFDM signals, from unit transmission waves of broadcast transport streams for a plurality of systems, concatenates the OFDM signals for the respective systems. To generate OFDM signals, the system arranges pilot signals, each having a specific phase, at prescribed positions in the frames, respectively. The system displaces the OFDM signals so that the pilot signal for any unit transmission wave may be identical in position and phase to the pilot signals for the two adjacent unit transmission waves having lower and higher frequencies, respectively.